If your microphone isn’t working with Talk&Type (formerly Speech Input), check to make sure you have granted permission for Read&Write for Google Chrome to access your microphone.
When you click the Talk&Type button on the Read&Write for Google Chrome toolbar, you should see a video camera icon appear in the Chrome address bar.
If the camera icon has a red X through it, this means access to your microphone has been blocked.
Click on the video camera icon, and in the dropdown menu select Continue allowing docs.google.com to access your microphone.
You should also check the Microphone dropdown list to be sure the correct microphone is selected.
Click Done to apply any changes.
When using Talk&Type, be sure to position your microphone in a way that your speech will be picked up. Speak clearly and at a moderate pace to ensure that your words are recorded accurately. An external microphone may produce better results than a built-in microphone on your computer or Chromebook.